Devonport swing bowler Chris Lindsay produced an outstanding finals performance to claim 6-35 as Ulverstone were skittled for 102.
Devonport and the Burnie Hurricanes will meet in the 2016-17 Cricket North-West first grade grade grand final next weekend.
Both team recorded first innings wins over Ulverstone and Latrobe in their respective grand finals.
The Orions staged a monumental comeback to defeat Ulverstone.
The Black Caps resumed at 1/46, needing a further 103 runs to overhaul Devonport’s total of 148, but a sensational spell from Chris Lindsay turned the game.
The Orions swing bowler produced an outstanding finals performance to claim 6-35 as Ulverstone were skittled for 102, with James Smith (22) the only batsman to pass 20.
Devonport then raced to 1-66 thanks to a blazing innings from Andre de Lange (44 from 34 balls) before Ulverstone conceded defeat.
The Burnie Hurricanes scored a convincing 151-run win over Latrobe n their semi-final.
The Demons made a bright start, reaching 3-108 shortly after lunch.
But their middle and lower order failed to fire and the home side was dismissed for 135.
Chris Boon (30), Neil Flack (30), Rhys French (26) and Nathan Avery (22) all made starts but the Hurricanes bowling depth shone through.
Off-spinner Pearce Watling was a standout for the visitors, claiming 3-17 from 19 overs to help the Hurricanes into a second successive grand final.
Devonport and Latrobe will meet in the second grade grand final after they defeated Wynyard and the Burnie Hurricanes respectively.
Centuries to Devonport’s Cody Brown and Latrobe’s Heath Davies helped their teams over the line.
The Cricket North-West grand final will be played from Friday to Sunday at West Park.